The present application relates to a drive device for a medical or dental tool, which is designed to convert a unidirectional rotational movement into a multidirectional rotational movement in order to operate the tool with this multidirectional movement.
A drive device, which converts a unidirectional rotational movement into a multidirectional movement in the form of a simultaneous or superimposed lifting and reduced-speed rotational movement, is known from the patent application WO 2011/089348 A1. This drive device, which is arranged in an angled handpiece, comprises a drive shaft, which can be connected to a motor and transmits a unidirectional rotational movement, a multistage planetary gear for reducing the rotational speed of the rotational movement, a shaft for transmitting the reduced-speed rotational movement and an eccentric shaft for generating the lifting movement.
This drive device has a number of disadvantages. To significantly reduce the rotational speed of the rotational movement, several planetary gears arranged in succession, for example, three planetary gears are provided, resulting in a need for a large amount of space. Because of this great need for space, the planetary gears can be arranged only in the rear section of the handpiece, which is at a distance from the head part of the angled handpiece and is separated by a bend or an angle (see FIG. 1 of WO 2011/089348 A1). However, then it is again necessary to provide two gears in the bend of the handpiece, a first gear for transmitting the reduced-speed rotational movement of the planetary gear and a second gear for transmitting the rotational movement to the eccentric shaft. Finally, the use of several planetary gears necessitates a variety of individual components and accordingly results in a high cost of manufacturing and assembly.
It would thus be desirable to create a drive device without the disadvantages mentioned above, such that it will convert a unidirectional rotational movement into a multidirectional movement in the form of a lifting and rotating movement, preferably simultaneously or superimposed, wherein the rotational speed of the rotational movement is preferably changed, in particular being reduced. In particular, the drive device should be as compact as possible, require little space, consist of a small number of individual parts, permit a great reduction in rotational speed and preferably be positionable between the angle and the head part of the angled handpiece.
Another drive device, which creates a multidirectional movement in the form of a multidirectional rotational movement, is known from U.S. Pat. No. 6,293,795 B1. This drive device comprises a handpiece, in particular an endodontic handpiece with a tool, for example, an endodontic file, which is driven by an electric motor. An electronic control unit including a microcontroller operates the electric motor in such a way that the file runs through a multidirectional rotational movement in the form of an oscillating rotational movement. The oscillating rotational movement comprises alternately a rotation of the tool about a first angle of rotation in a first direction of rotation and about a second angle of rotation in a second direction of rotation in the opposite direction, such that the first and second angle of rotations have different amounts. Due to the oscillating rotational movement tissue is removed, in particular tissue in the dental root canal, preferably by rotation of the tool in one direction of rotation, and this tissue is conveyed in the direction of the dental crown, preferably by rotation of the tool in the opposite direction of rotation.
One disadvantage of this drive device is that an electric control unit including a microcontroller is required for operation of the tool. There is thus a substantial additional technical and financial cost required for implementation of the oscillating rotational movement, in particular for users who have a treatment device that is operated only pneumatically.
Accordingly, it would be desirable to create an alternative drive device that would induce an oscillating rotational movement of a medical or dental tool and in particular could also be used with treatment equipment that is operated only pneumatically.